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Build double-entry invoicing against Czech law with Claude Code in three days
WorkedEvidence: Described by posterPosted Last checked
Jiří Dolejš used Claude Code for a ~3,430-line Czech-law accounting spec and shipped double-entry invoicing in three days.
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Build an invoicing system with double-entry bookkeeping, accountant export formats, cash-flow tracking and bank payment matching. First produce a complete specification checked against Czech accounting legislation, then implement against that spec.
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Before you start, ask me 1–3 short questions about the details below and wait for my answers. Once I've answered, confirm the plan in one line and run the whole task start to finish. Goal: Ship a legislation-aware invoicing and double-entry system instead of renting SaaS. Questions to ask me first: - Which country's accounting rules apply? - Which export format does your accountant require? - Which bank feeds or CSV formats must match payments? Inputs (fill in or confirm): - Jurisdiction and entity type: [NOTES] - Must-have features: [LIST] - Sample invoices and chart of accounts: [FILES] Rules: - Write the legislation-backed spec before coding features. - Cite sources in the spec; flag uncertain interpretations. - Keep an audit trail for every posting. - Have a human accountant review before production use. Checkpoint: Review the spec outline and source list before implementation starts. If you get stuck: If a legal citation conflicts, stop and ask rather than picking silently. Verify before you finish: Post a sample invoice both ways and confirm the accountant export opens cleanly. Output: Spec summary, working invoicing flows and a short accountant handoff note. Done when: I can invoice, post double-entry and export for my accountant.
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Outcome
Jiří George Dolejš needed invoicing with true double-entry bookkeeping, accountant exports, cash-flow tracking and bank matching — not a generic SaaS. With Claude Code, Day 1 produced invoicing; Days 2–3 added double-entry. The key artifact was a legislation-checked specification: about 3,430 lines across 17 sections and 11 appendices citing 142 sources, plus another ~2,100-line extension, generated against Czech accounting rules. Overnight build iterations shipped while Dolejš slept. The result is a working system Dolejš says would normally take a senior developer at least three weeks.
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Source
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- by Jiří George Dolejš
- Last checked
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- How we verify
https://jiridolejs.cz/en/blog/invoicing-system-in-2-days
Context: URL slug says 2 days; body says invoicing in 1 day and double-entry in 2 more (3 total). Spec line counts from the author.
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